Viability and depletion of cell constituents of Methanospirillum hungatii GP1 during starvation

The viability of Methanospirillum hungatii GP1 cells dropped rapidly when starved in a pH 7.0 phosphate buffer under 100% N2 or 90% N2 - 10% H2 gas phase. The presence of H2 during starvation tests resulted in a more rapid and an ultimately greater reduction of the number of initially viable cells than in the presence of N2 only. The decrease in viability was observed concurrently with the decline of the ATP pool and the RNA content of the cells. The cell protein, carbohydrate, and amino acid pool also decreased. The cellular DNA content which increased initially under both gas phases subsequently decreased under N2-H2 gas phase. However, there was no net decline in the DNA content of the cells. The results indicate that M. hungatii would not survive prolonged periods of starvation.